Types of cylinders with these characteristics are known are known through references FR-A-2,661,229 and EP-1158201-A1 in favour of the applicant.
In these references, the valve cap and the shaft cap are conceived by means of the union of components which can be coupled together, and between which the passageways for the gas to pass from one chamber to the other are formed.
In the same way, the valve shaft is elongated and protrudes outside the cylinder, and is also provided with a dynamic ring seal that closes or opens over the front of the lower part among those that make up the valve cap, so that when the shaft moves due to its being operated from the exterior, the passage of gas is opened from the upper intermediate chamber between the cylindrical bodies.
The operation of the said shaft from the exterior is usually carried out by means of a lever, which provides sufficient power movement to move the valve shaft without any problem in order to adjust the position of the cylinder shaft.
More recently, however, the technique of using push-buttons, switches, etc. to operate the valve shaft is becoming more widespread, with which the force to be applied through the user's finger must be considerably lower than is traditional, of about 1.5 to 1.7 kg., which leads to shaft traverses or strokes which are very limited, for instance of the order of 1.5 to 2 nm.
This trend has brought about a variation in the traditional arrangements of the movement of the valve shaft, because on many occasions its movements are carried out based on cables or wires operated by the previously mentioned push-buttons.
Therefore, the axial movements have become lateral or circular movements, thanks to the pivoting of the value shaft when it is operated by the exterior control.